1. Field of the Invention
This invention relates to a feeder for supplying fibers to an apparatus for forming a preliminary web, comprising a holding shaft, which is adapted to be supplied with fibers from above from a conveying line and is closed at the bottom by at least one discharge roller, and a distributor, which is disposed between the holding shaft and the conveyor line and serves to distribute the arriving stream of fibers over the width of the shaft in the axial direction of the discharge roller, wherein the distributor comprises at least two distributing lines, which serve to receive fibers from the conveying line and open into the holding shaft at locations which are distributed over the width of the shaft.
2. Description of the Prior Art
It is known that a preliminary web which is as uniform as possible can be supplied, e.g., to a card in that the fibrous material is first supplied to a holding shaft from above from a conveyor line and the fibrous material is discharged from the holding shaft by at least one discharge roller, which closes the holding shaft at its bottom, whereafter the belt conveyor forwards the discharged fibers onto an elevator lattice, which is succeeded by a vibrating shaft for forming a so-called flake mat, which is then fed as a preliminary web to the card for further processing. The uniformity of such preliminary web will depend on the uniformity of the stream of fibers discharged from the holding shaft over the length of the discharge roller and said uniformity requires a uniform distribution of the fibers supplied to the holding shaft over the width of said shaft, which width extends in the axial direction of the discharge roller. To permit a uniform distribution over a substantial shaft width of the stream of fibers which are supplied from a suitable conveying line, various distributors have been employed and it has been found that distributors comprising a distributing tube which is reciprocable over the width of the shaft are superior to those distributors which comprise a distributing line which flares like an inverted funnel over the width of the shaft. The known distributor comprising a moving distributing tube have the disadvantage that the structural expenditure is relatively high and, above all, that clearance spaces will necessarily occur in the transitional region between the stationary conveyor line and the moved distributing tube and fibers may deposit in such clearance spaces so that the movement of the distributing tube will be restrained and said deposited fibers may initiate a formation of substantial accumulations of fibers, by which the conveyance of the fibers is highly adversely affected. These remarks are applicable to distributors comprising a pendulum tube, which swings over the width of the shaft, and to distributors which comprise a distributing tube that is parallel to the discharge roller and can be telescopically extended and retracted.
From British Patent Specification No. 1,422,861 it is known to provide a distributor which comprises two distributing lines, which are adapted to be connected to a conveying line and which open into the holding shaft at locations which are distributed over the width of the shaft. That known distributor has the disadvantage that the distribution of the fibers to the two distributing lines is pneumatically effected by a control of the air supply so that it is not possible to close one of the two distributing lines and the distribution of the fibers over the width of the shaft will be disturbed because a predetermined distribution of fibers cannot readily be maintained.